Saving Lives by Detecting Tsunamis Sooner

On December 26, 2004 an undersea earthquake in the Indian Ocean caused the deadliest tsunami in recorded history. The magnitude 9.1 earthquake triggered 30-metre high waves that destroyed entire communities in Southeast Asia, leaving almost 230,000 people dead or missing. Nearly all of the victims were caught by surprise, with no time to escape the deadly waves.

In July, a smaller tsunami struck Java Island in Indonesia, killing hundreds of people and displacing thousands more who had already escaped the devastating 2004 tsunami. Again, there was little warning of the impending disaster.

These tragic cases demonstrate the importance of tsunami detection and warning systems that can save lives by giving people a chance to get out of disaster's path.

LewHill Testing Technologies, an incubator company located at the NRC Institute for Ocean Technology (NRC-IOT) in St. John's, Newfoundland, has developed a better system for detecting tsunamis – one that could reduce the scale of future tragedies by saving thousands of lives.

Using software to improve sensor accuracy

LewHill Sensor

The tsunami detection technology is the result of a software program designed by Tom Lewis, founder of LewHill Testing Technologies. The software, called Oscillating Shrinking Data Window, or OSDAW for short, makes sensors more accurate. It was originally designed as a calibration tool for Lotek Wireless, a company that develops fish and wildlife monitoring systems that was looking for a better way to calibrate sensors used to track animals.

Lewis had toyed with the idea of applying the OSDAW software to pressure sensor systems that detect tsunamis, but he soon discovered that although there was much talk about tsunami detection, few people seemed willing to invest in developing the technology.

But when the Southeast Asian tsunami struck in 2004, everything changed. Suddenly, there was a huge demand for LewHill's technology.

Small changes indicate big danger

It's not easy to detect a tsunami under deep water. Even if you were sitting in a boat directly above a tsunami-triggering undersea event, you might not notice a difference in the water level. That's because the amplitude (height) of tsunami waves is much lower in the middle of the ocean than when the waves reach the coast.

The "surface noise" in the ocean – the overall difference in the water level as waves rise and fall – is usually no more than three millimeters. LewHill's tsunami detection system uses sensors on the ocean floor to detect differences in the ocean's water pressure and columns. When the water rises more than five millimeters, the detectors start recording, and within minutes, they determine whether or not they have detected a tsunami event.

The recorded information is sent to the surface via buoys and transmitted to monitoring officials via satellite. A Global Positioning System identifies the exact location of the sensor that recorded the event. With this information in hand, officials can issue tsunami warnings anywhere from two to ten hours in advance of landfall (depending on the location), giving people plenty of time to move to higher ground, potentially saving their lives.

The system has significant advantages over existing monitoring devices that use seismic data and are unable to predict every tsunami.

Benefiting from NRC expertise

In addition to incubating at NRC's facility in St. John's, LewHill benefited from a variety of NRC expertise throughout the design process, including NRC's skilled machine shop and electronics staff, wave experts and research and development staff. NRC's unique wave facilities were also essential during testing.

Tsunamis can be as big as 500 to 1000 kilometres long, making them impossible to simulate in a lab setting. To test LewHill's sensors, NRC researchers had to develop new models for simulating wavelengths in deep water. They used a pressure bladder to raise and lower the water level in the NRC Ocean Engineering Basin wave tank.

Lewis emphasized the professionalism of NRC staff who were eager to take on a seemingly-impossible task. He said his work benefited from the proximity of NRC expertise and facilities through the incubator relationship.

"When you first start a company, some of the things you think would be problems aren't, and some that you didn't think about are," Lewis says. "It's nice to have someone to talk to, shoulders to cry on when you first start... At NRC they've been through it all."

Riding a wave of success

Now that research and development of the tsunami detection system is complete, Lewis is turning his attention to marketing and licensing the OSDAW technology for manufacture.

Sensors are already being used in the Pacific Ocean, mostly near the United States and Vancouver, but plans are afoot to expand to Southeast Asia and to integrate with existing systems in Japan. Eventually, there will be a 75-buoy array in the Pacific, with further expansion planned for the Atlantic Ocean.

LewHill Testing Technologies has been contacted by university and industry partners and government organizations bidding for contracts to use the technology. The US military has already adopted OWSDA as a calibration system for depth sensors. 

Advanced warning saves lives

Improving tsunami detection has been a rewarding experience for Tom Lewis, who loves a challenging problem. "For me, that's my interest: being presented with a technical challenge, then coming up with an innovative way to overcome it," he says. "That's where I get my kicks."

Even more rewarding, however, is the knowledge that this new tsunami detection device has the potential to save many lives around the world by ensuring no one is ever caught off guard by a tsunami's terrifying waves again.

Potential tsunami detection system. Courtesy of NOAA/ U.S. National Data Buoy Centre.

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